Methods for depositing blocking layers on conductive surfaces

ABSTRACT

Methods of selectively depositing blocking layers on conductive surfaces over dielectric surfaces are described. In some embodiments, a carboxylic acid is exposed to a substrate to selectively form a blocking layer. In some embodiments, a hydrazide is exposed to a substrate to selectively form a blocking layer. In some embodiments, an alkyl phosphonic acid is exposed to a substrate to selectively form a blocking layer. In some embodiments, the alkyl phosphonic acid is formed in-situ and exposed to the substrate. In some embodiments, a layer is selectively deposited on the dielectric surface after the blocking layer is formed.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a divisional application of U.S. patent applicationSer. No. 16/229,659, filed Dec. 21, 2018, which claims priority to U.S.Provisional Application No. 62/610,147, filed Dec. 22, 2017, the entiredisclosure of which is hereby incorporated by reference herein.

FIELD

Embodiments of the disclosure relate methods for depositing blockinglayers on conductive surfaces. More particularly, embodiments of thedisclosure are directed to methods of depositing blocking layers onconductive surfaces to facilitate the deposition of films on thedielectric surfaces of patterned substrates.

BACKGROUND

The semiconductor industry faces many challenges in the pursuit ofdevice miniaturization which involves rapid scaling of nanoscalefeatures. Such issues include the introduction of complex fabricationsteps such as multiple lithography steps and integration of highperformance materials. To maintain the cadence of deviceminiaturization, selective deposition has shown promise as it has thepotential to remove costly lithographic steps by simplifying integrationschemes.

Selective deposition of materials can be accomplished in a variety ofways. A chemical precursor may react selectively with one surfacerelative to another surface (metallic or dielectric). Process parameterssuch as pressure, substrate temperature, precursor partial pressures,and/or gas flows might be modulated to modulate the chemical kinetics ofa particular surface reaction. Another possible scheme involves surfacepretreatments that can be used to activate or deactivate a surface ofinterest to an incoming film deposition precursor.

There is an ongoing need in the art for treatment methods to deactivateor block conductive surfaces.

SUMMARY

One or more embodiments of this disclosure relate to a method ofselectively depositing a blocking layer. The method comprises exposing asubstrate comprising a conductive material having a first surface and adielectric material having a second surface to a carboxylic acid toselectively form a blocking layer on the first surface over the secondsurface and form a blocked first surface. The carboxylic acid comprisesat least one compound with a general formula RCOOH, where R is selectedfrom C4-C20 alkyl, perfluoroalkyl, alkenyl or alkynyl groups.

Additional embodiments of this disclosure relate to a method ofselectively depositing a blocking layer. The method comprises exposing asubstrate comprising a conductive material having a first surface and adielectric material having a second surface to a hydrazide toselectively form a blocking layer on the first surface over the secondsurface and form a blocked first surface. The hydrazide comprises atleast one compound with a general formula RC(O)NHNR′₂, where R isselected from C4-C20 alkyl, perfluoroalkyl, alkenyl or alkynyl groupsand each R′ is independently selected from H or C1-C4 alkyl or can jointogether to form a ring comprising 2 to 5 carbon atoms.

Further embodiments of this disclosure relate to a method of selectivelydepositing a blocking layer. The method comprises exposing a substratecomprising a conductive material having a first surface and a dielectricmaterial having a second surface to a gaseous alkyl phosphonic acid toselectively form a blocking layer on the first surface over the secondsurface and form a blocked first surface. The alkyl phosphonic acidcomprises at least one compound with a general formula RP(O)(OR″)₂,where R is selected from C4-C20 alkyl, perfluoroalkyl, alkenyl oralkynyl groups and each R″ is independently selected from H, C1-C12alkyl or aryl.

BRIEF DESCRIPTION OF THE DRAWING

So that the manner in which the above recited features of the presentdisclosure can be understood in detail, a more particular description ofthe disclosure, briefly summarized above, may be had by reference toembodiments, some of which are illustrated in the appended drawings. Itis to be noted, however, that the appended drawings illustrate onlytypical embodiments of this disclosure and are therefore not to beconsidered limiting of its scope, for the disclosure may admit to otherequally effective embodiments.

The FIGURE illustrates a processing method in accordance with one ormore embodiment of the disclosure.

In the appended FIGURES, similar components and/or features may have thesame reference label. Further, various components of the same type maybe distinguished by following the reference label by a dash and a secondlabel that distinguishes among the similar components. If only the firstreference label is used in the specification, the description isapplicable to any one of the similar components having the same firstreference label irrespective of the second reference label.

DETAILED DESCRIPTION

Embodiments of the disclosure provide methods for selectively depositingblocking layers on conductive surfaces. Embodiments of the disclosureidentify methods for depositing blocking layers which may be usedseparately or in conjunction.

A “substrate surface”, as used herein, refers to any portion of asubstrate or portion of a material surface formed on a substrate uponwhich film processing is performed. For example, a substrate surface onwhich processing can be performed include materials such as silicon,silicon oxide, silicon nitride, doped silicon, germanium, galliumarsenide, glass, sapphire, and any other materials such as metals, metalnitrides, metal alloys, and other conductive materials, depending on theapplication. Substrates include, without limitation, semiconductorwafers. Substrates may be exposed to a pretreatment process to polish,etch, reduce, oxidize, hydroxylate, anneal, UV cure, e-beam cure and/orbake the substrate surface. In addition to film processing directly onthe surface of the substrate itself, in the present disclosure, any ofthe film processing steps disclosed may also be performed on anunderlayer formed on the substrate as disclosed in more detail below,and the term “substrate surface” is intended to include such underlayeras the context indicates. Thus for example, where a film/layer orpartial film/layer has been deposited onto a substrate surface, theexposed surface of the newly deposited film/layer becomes the substratesurface. Substrates may have various dimensions, such as 200 mm or 300mm diameter wafers, as well as, rectangular or square panes. In someembodiments, the substrate comprises a rigid discrete material.

Embodiments of the disclosure advantageously provide methods forselectively forming a blocking layer on a conductive surface over adielectric surface. Some embodiments advantageously provide furthermethods to selectively deposit a layer on a dielectric surface.

As used in this specification and the appended claims, the phrase“conductive surface” or “dielectric surface” means that the surfacerelates to a material with the stated property. Accordingly, aconductive surface is the surface of a conductive material, but nostatement is being presented regarding the conductivity of the surfaceper say. Similarly, a dielectric surface is the surface of a dielectricmaterial.

As used in this specification and the appended claims, the term“selectively depositing a film on one surface over another surface”, andthe like, means that a first amount of the film is deposited on thefirst surface and a second amount of film is deposited on the secondsurface, where the second amount of film is less than the first amountof film, or no film is deposited on the second surface. The term “over”used in this regard does not imply a physical orientation of one surfaceon top of another surface, rather a relationship of the thermodynamic orkinetic properties of the chemical reaction with one surface relative tothe other surface. For example, selectively depositing a cobalt filmonto a copper surface over a dielectric surface means that the cobaltfilm deposits on the copper surface and less or no cobalt film depositson the dielectric surface; or that the formation of the cobalt film onthe copper surface is thermodynamically or kinetically favorablerelative to the formation of a cobalt film on the dielectric surface. Insome embodiments, “selectively” means that the subject material forms onthe selective surface at a rate greater than or equal to about 10×, 15×,20×, 25×, 30×, 35×, 40×, 45× or 50× the rate of formation on thenon-selected surface. Stated differently, the selectivity for thesubject material relative to the non-selected surface is greater than orequal to about 10:1, 15:1, 20:1, 25:1, 30:1, 35:1, 40:1, 45:1 or 50:1.

Some embodiments of the disclosure incorporate a blocking layertypically referred to as a self-assembled monolayer (SAM). Aself-assembled monolayer (SAM) consists of an ordered arrangement ofspontaneously assembled organic molecules adsorbed on a surface. Thesemolecules are typically comprised of one or more moieties with anaffinity for the substrate (head group) and a relatively long, inert,linear hydrocarbon moiety (tail group).

In this case, SAM formation happens through fast adsorption of molecularhead groups at the surface and slow association of molecular tail groupswith each other through van der Waals interactions. SAM precursors arechosen such that the head group selectively reacts with the substratematerials to be blocked during deposition. Deposition is then performed,and the SAMs can be removed through thermal decomposition (withdesorption of any byproducts) or an integration-compatible ashingprocess.

One or more embodiments of this disclosure are directed to methods ofselectively depositing a blocking layer on a first surface of asubstrate over a second surface. The first surface is a surface of aconductive material. The second surface is a surface of a dielectricmaterial.

The conductive material of the substrate may be any suitable material.Suitable conductive materials include, but are not limited to, metals,metal nitrides, some metal oxides, metal alloys, combinations thereofand other conductive materials. In some embodiments, the conductivematerial comprises one or more of chromium, manganese, iron, copper,nickel, cobalt, tungsten, ruthenium, tantalum oxide, tantalum nitride,titanium oxide or titanium nitride. In some embodiments, the conductivematerial consists essentially of chromium, manganese, iron, copper,nickel, cobalt, tungsten, ruthenium, tantalum oxide, tantalum nitride,titanium oxide or titanium nitride. As used in this specification andthe appended claims, the term “consists essentially of” means that thematerial is greater than or equal to about 95%, 98% or 99% of the statedmaterial on an atomic basis.

As used in this specification and the appended claims, the term “oxide”or the like means that the material contains the specified element(s).The term should not be interpreted to imply a specific ratio ofelements. Accordingly, an “oxide” or the like may comprise astoichiometric ratio of elements or a non-stoichiometric ratio ofelements.

The dielectric material of the substrate may be any suitable material.Suitable dielectric materials include, but are not limited to, siliconoxides (e.g. SiO₂), silicon nitrides, silicon carbides and combinationsthereof (e.g. SiCON). In some embodiments, the dielectric materialconsists essentially of silicon dioxide (SiO₂). In some embodiments, thelayer comprises silicon nitride. In some embodiments, the layer consistsessentially of silicon nitride.

Referring to the FIGURE, a generalized method 100 begins with asubstrate 105 comprising a conductive material 110 having a firstsurface 112 and a dielectric material 120 having a second surface 122.The substrate 105 is exposed to a blocking compound (not shown) toselectively form a blocking layer 130 on the first surface 112 over thesecond surface 122 and form a blocked first surface 132.

In some embodiments, the method 100 continues by selectively depositinga layer 125 on the second surface 122 over the blocked first surface132. In some embodiments, the layer 125 is a dielectric material. Insome embodiments, the layer comprises silicon nitride.

Deposition of silicon nitride can be performed through any suitableprocess. Suitable processes may include exposure of the substrate to asilicon halide and ammonia. Suitable silicon halides include, but arenot limited to dichlorosilane (DCS), trichlorosilane (TCS),tetrachlorosilane (SiCl₄), tetrabromosilane (SiBr₄), tetraiodosilane(SiI₄), and hexachlorodisilane (HCDS).

In some embodiments, the silicon nitride layer is deposited with athickness in the range of about 10 Å to about 50 Å, or in the range ofabout 12 Å to about 35 Å, or in the range of about 15 Å to about 20 Å.In some embodiments, formation of the blocking layer and deposition ofthe layer are repeated until the layer has a thickness of greater thanor equal to about 50 Å, greater than or equal to about 75 Å, greaterthan or equal to about 100 Å or greater than or equal to about 150 Å.

In some embodiments, the method 100 continues by removing the blockinglayer 130 to expose the first surface 112. In some embodiments, theblocking layer 130 is removed using selective etching processes.Oxygen-based and fluorine-based etches are known to etch carbon basedfilms similar to the blocking layer disclosed herein.

One non-limiting example is removing the blocking layer via anoxygen-based remote plasma. In this example the oxygen-based remoteplasma etch removes the blocking layer but also oxidizes the firstsurface. To recover the original surface composition, the surface can bereduced. Suitable reduction processes include, but are not limited to,the use of plasmas comprising hydrogen or ammonia and thermal annealscomprising hydrogen or ammonia. In some embodiments, the oxygen plasma,fluorine plasma, hydrogen plasma and ammonia plasma can be independentlyremotely or internally generated, and conductively coupled orinductively coupled.

Although not shown in the FIGURE, methods of this disclosure may furthercomprise cleaning the first surface before exposing the substrate to theblocking compound. In some embodiments, cleaning the first surfacecomprises exposing the first surface to a solution comprising aceticacid and ethanol. In some embodiments, the solution is a 10% ethanolicsolution of acetic acid (i.e., 10% v/v acetic acid in ethanol or 10% w/wacetic acid in ethanol). In some embodiments, cleaning the first surfacecomprises exposing the first surface to a plasma of hydrogen gas (H₂).In some embodiments, the hydrogen plasma is a conductively coupledplasma (CCP). In some embodiments, the hydrogen plasma is an inductivelycoupled plasma (ICP). Without being bound by theory, it is believed thatcleaning the first surface results in a higher prevalence ofH-terminations on the first surface. These terminations are believed tobe the reaction sites for the blocking compound.

In some embodiments, the blocking compound comprises a carboxylic acid.In some embodiments, the method comprises exposing a substratecomprising a conductive material having a first surface and a dielectricmaterial having a second surface to a carboxylic acid to selectivelyform a blocking layer on the first surface over the second surface andform a blocked first surface.

In some embodiments, the carboxylic acid comprises at least one compoundwith a general formula RCOOH, where R is selected from C4-C20 alkyl,perfluoroalkyl, alkenyl or alkynyl groups. As used in this manner, theletter “C” followed by a numeral (e.g., “C4”) means that the substituentcomprises the specified number of carbon atoms (e.g., C4 comprises fourcarbon atoms). In some embodiments, C4-C20 alkyl groups consistessentially of C—C single bonds and C—H bonds. In some embodiments,C4-C20 perfluoroalkyl groups consist essentially of C—C single bonds andC—F bonds. In some embodiments, C4-C20 alkenyl groups consistessentially of C—C single bonds, at least one C—C double bond and C—Hbonds. In some embodiments, C4-C20 alkynyl groups consist essentially ofC—C single bonds, at least one C—C triple bond and C—H bonds. In someembodiments, the C4-C20 groups include one or more halogen atom and/orother hydrophobic moiety. In some embodiments, the C4-C20 groups can bea straight chain groups (e.g. n-butyl), a branched groups (e.g. t-butyl)or a cyclic groups (e.g. cyclohexyl). In some embodiments, the alkyl,perfluoroalkyl, alkenyl or alkynyl group is a straight chain. In someembodiments, the alkyl, perfluoroalkyl, alkenyl or alkynyl group is abranched chain.

In some embodiments, the carboxylic acid comprises heptanoic acid,octanoic acid, undecanoic acid or ocadecanoic acid. In some embodiments,the carboxylic acid consists essentially of undecanoic acid.

In some embodiments, a long chain carboxylic acid can be used as ablocking molecule and reacted with a metal surface (with or withoutnative oxide). In some embodiments, the exposure to the carboxylic acidis performed in solution. In some embodiments, the exposure to thecarboxylic acid is performed in vapor phase.

In some embodiments, small and medium chain length (<C12) carboxylicacids are delivered in vapor phase. In some embodiments, long alkylchain (≥C12) carboxylic acids can be used as blocking compounds insolution phase.

Without being bound by theory, metals (including but not limited to Cu,Co, W, Ru, TiN) are usually oxophilic and bind to carboxylic acidpreferentially as RCOO-M over SiO₂ or SiN surface.

In some embodiments, a layer of silicon nitride is selectively depositedon the second surface over the first blocked surface. In someembodiments, a thickness of the layer of silicon nitride is in the rangeof about 30 Å to about 40 Å. In some embodiments, the layer of siliconnitride is deposited with a selectivity of greater than or equal toabout 30:1. In some embodiments, the substrate is maintained at atemperature of less than or equal to about 200° C.

In some embodiments, the blocking compound comprises a hydrazide. Insome embodiments, the method comprises exposing a substrate comprising aconductive material having a first surface and a dielectric materialhaving a second surface to a hydrazide to selectively form a blockinglayer on the first surface over the second surface and form a blockedfirst surface.

In some embodiments, the hydrazide comprises at least one compound witha general formula R—C(O)NHNR′₂, where R is selected from C4-C20 alkyl,perfluoroalkyl, alkenyl or alkynyl groups and each R′ is independentlyselected from H or C1-C4 alkyl or can join together to form a ringcomprising 2 to 5 carbon atoms.

Without being bound by theory, hydrazides are expected to form thermallystable metal complexes. Cobalt-hydrazide complexes such asbis(tert-butyl carbohydrazido)cobalt is relatively less volatile andthermally stable up to 250° C. It is believed that using a longer chainalkyl group can further reduce the vapor pressure and lead to blockingof a conductive surface.

In some embodiments, R is a t-butyl group. In some embodiments, each R′is hydrogen. In some embodiments, each R′ is a methyl group.

In some embodiments, the blocking compound comprises a gaseous alkylphosphonic acid. In some embodiments, the method comprises exposing asubstrate comprising a conductive material having a first surface and adielectric material having a second surface to a gaseous alkylphosphonic acid to selectively form a blocking layer on the firstsurface over the second surface and form a blocked first surface. Asused in this specification and the appended claims, the descriptor“gaseous” means that the alkyl phosphonic acid is supplied in the vaporphase.

In some embodiments, the alkyl phosphonic acid comprises at least onecompound with a general formula R—P(O)(OR″)₂, where R is selected fromC4-C20 alkyl, perfluoroalkyl, alkenyl or alkynyl groups and each R″ isindependently selected from H, C1-C12 alkyl or aryl.

In some embodiments, the R″ is independently a C1-C12 alkyl or aryl.Without being bound by theory, the lack of hydrogen bonding in the alkylphosphonic acids of these embodiments increase the vapor pressure ofthese blocking compounds.

In some embodiments, the alkyl phosphonic acid comprises octadecylphosphonic acid. In some embodiments, the alkyl phosphonic acidcomprises perfluorooctyl phosphonic acid.

In some embodiments, the alkyl phosphonic acid is generated in situ bythe reaction of a dihaloalkylphosphonic acid and an alcohol. In someembodiments, the dihaloalkylphosphonic acid comprises at least onecompound with a general formula RP(O)X₂, where each X is anindependently selected halogen. In some embodiments, the alcoholcomprises at least one compound with a general formula R″OH.

Without being bound by theory, the dihaloalkylphosphonic acid and thealcohol are each more volatile than the alkyl phosphonic acid which theyproduce. Accordingly, it is possible to deliver both thedihaloalkylphosphonic acid and the alcohol in the vapor phase such thatthey react to form an alkyl phosphonic acid which would otherwise bedifficult to volatilize.

In some embodiments, R″ is H. Without being bound by theory, the use ofwater as the alcohol of these embodiments provides alkyl phosphonicacids in situ which would otherwise have low volatility due to hydrogenbonding.

Although the disclosure herein has been described with reference toparticular embodiments, it is to be understood that these embodimentsare merely illustrative of the principles and applications of thepresent disclosure. It will be apparent to those skilled in the art thatvarious modifications and variations can be made to the method andapparatus of the present disclosure without departing from the spiritand scope of the disclosure. Thus, it is intended that the presentdisclosure include modifications and variations that are within thescope of the appended claims and their equivalents.

What is claimed is:
 1. A method of selectively depositing a blockinglayer, the method comprising exposing a substrate comprising aconductive material having a first surface and a dielectric materialhaving a second surface to a hydrazide to selectively form the blockinglayer on the first surface over the second surface and form a blockedfirst surface, the hydrazide comprising at least one compound with ageneral formula RC(O)NHNR′₂, where R is selected from C4-C20 alkylgroup, C4-C20 perfluoroalkyl group, C4-C20 alkenyl group or C4-C20alkynyl group and each R′ is independently selected from H or C1-C4alkyl or joins together to form a ring comprising 2 to 5 carbon atoms.2. The method of claim 1, wherein the conductive material comprises ametal, metal alloy, metal oxide, metal nitride, or a combinationthereof.
 3. The method of claim 2, wherein the conductive materialcomprises one or more of chromium, manganese, iron, copper, nickel,cobalt, tungsten, ruthenium, tantalum oxide, tantalum nitride, titaniumoxide or titanium nitride.
 4. The method of claim 1, further comprisingselectively depositing a layer on the second surface over the blockedfirst surface.
 5. The method of claim 4, wherein the layer comprises adielectric material.
 6. The method of claim 1, wherein R is a t-butylgroup.
 7. The method of claim 1, wherein each R′ is hydrogen.
 8. Themethod of claim 1, wherein each R′ is a methyl group.